Monday, October 19, 2015

Follow The Yellow Brick Road vs Pavement's Many Problems

Jessup, my street in Philly
Let's hit the bricks!  Really. The time for bricks (i.e., pavers) on our streets and sidewalks has come and gone… and come back again!  We’ve wasted enough time and resources on pavement.   Pavement doesn’t work.  And it doesn’t matter if the pavement is made of asphalt or concrete.

This is a subject close to my heart for a couple of reasons.  I’m old enough to have witnessed hundreds of roads, both in the suburbs and city, getting repaved repeatedly.  And then the inevitable happens.  That silky smooth surface barely lasts a month before someone is digging it up to lay a pipe or cable or something.  I always shake my head and think, “What a waste. When will they learn?” 

Then in 2012, I had my chance to do something about it.  My husband Cliff and I founded a group to help repair and restore old small streets.  It’s called The Philadelphia Society of Small Streets ( And that's what really propelled me (pardon the pun) down the road and into “pavers” as the best solution to our current 'street construction calamity'.

What's wrong with pavement?  Just about everything.  Pavement has 5 things going against it.  First and foremost, it hides any subsidence occurring underground until it become dangerous, if not catastrophic.  Think deep sinkholes and giant wormholes created from stormwater runoff and/or leaky pipes.  Second, pavement cannot be easily or ‘quietly’ removed without the use of heavy equipment, thereby creating vibration problems for nearby structures, including buildings above and utilities below.  Third, pavement cracks.  Any repairs made to pavement inevitably creates an uneven patchwork quilt that is both unsightly and unsafe for pedestrians and vehicles alike.  Fourth, in the case of asphalt, it's basically toxic waste product of the petroleum industry.  In the case of concrete, it can also be risky if it includes toxic incinerator ash.  And fifth, pavement increases storm water runoff.  To sum up, both asphalt and concrete pavement present inordinate structural, aesthetic, environmental, and health problems.

On the other hand, pavers (if not made of toxic asphalt or toxic concrete) are fairly easy peasy. Almost anyone can lay them.  It's not rocket science, although it should be done with care. For a good example of "paver street construction”, the Netherland’s model seems a good bet.  Keep in mind, the foundation should not be made of concrete, otherwise you’d be repeating the mistakes of pavement. Instead, the foundation should consist of 15 inches of pulverized concrete (although we prefer "modified aggregate" stones) and on top, 2-6 inches of sand of good quality, not like the sand on a beach (although we have used screenings from the aggregate stones instead). And the pavers should fit close together. See:  (Not a product endorsement) 

The great thing about pavers is that they serve as an "early warning system" for any subsidence problems below ground.  They just start to slowly collapse into the hole, giving city officials and property owners a chance to fix things before people, cars, and building start disappearing into a potentially vast cavern beneath the pavement, something that appears to happening in Pennsylvania with increased frequency. See -  / 

Then you have the advantages pavers hold in the area of stormwater runoff.  Pavers, in combination with an aggregate foundation, allow for a reasonable amount of permeability. I call it "the slow-soak" method.  That's in contrast to Philadelphia's "Green Street" model for Philly's small streets.  In that case, the city is using asphalt which is not "green" at all, but instead quite toxic.  Secondly, it actually creates a cistern under the streets, using clean stones and lined on either side of the road with plastic, that they claim will protect nearby basements from water damage.  However, typically plastic liners, even landfill liners, are only 1/10 of an inch thick and are vulnerable to cracking and breaking due to heat and cold, wear and tear. Our research shows that buried "impermeable" plastic liners only last from 15-20 years. Not good news for homeowners. 

We're not just talking about streets here.  Pavement on sidewalks creates the same situation.  So, how do you lay a sidewalk?   Some people use aggregate, sand, and/or screening, although in much smaller amounts than for "paver street construction" due to lighter loads and usage.  Other people, like in my neighborhood, just use the soil that they have on site.  It depends on conditions.  

Camac in better days
Lastly, I haven’t mentioned wood pavers, but there is an interesting history of using wood on streets in many countries, including the U.S. in the early 1800’s. We put together a special webpage for wood streets,  However, it appears from our research that wood streets around the world have been poorly built, historically. 

There is evidence that the wrong type of wood was used to make the wood blocks (usually pine or oak), and those wood blocks were often placed upon impermeable foundations. We’ve suggested to the Streets Department in Philadelphia that they consider experimenting with more appropriate woods, such as Black Locust, Osage Orange, and maybe a local Cedar or Cypress.  So far, no deal, but we live in hope.  That said, there may be nothing stopping homeowners from installing wood sidewalks.  I haven’t checked on that with the Streets Department yet to see if its in code…because I just thought about it.  I think this is what's called an epiphany.  Feels good.

But the main point I’m trying to make is that pavers have it all over pavement when it comes to structural, aesthetic, environmental, and health advantages.  So, there you have it.  Leave the pavement behind.  Go follow that Yellow Brick Road. And Get Sensical!  

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